生物炭、蒙脱石及其混合添加对复合污染土壤中重金属形态的影响

本文以采自湖南临湘某重金属复合污染的土壤为研究材料,采用室内培养方法,将生物炭(BC)和蒙脱石(MM)按1%、2%、5%单独添加,以及将二者混合添加(1%+1%),通过BCR连续提取法,研究不同钝化剂对复合污染土壤重金属形态变化的影响.结果表明,生物炭处理显著降低了Cu、Pb和Cd的有效态含量.蒙脱石处理中,MM5%处理使Cu、Pb、Zn、Cd的弱酸提取态含量分别降低了27.6%、19.2%、25.6%、19.2%.混合钝化剂处理使Cu、Pb、Zn、Cd的弱酸提取态含量分别降低了15.8%、15.9%、13.1%、12.0%,残渣态含量分别增加了39.0%、110.1%、9.6%、62.5%,显著降低了4种元素的移动性.蒙脱石钝化效果整体优于生物炭,两者结合使用效果更佳.

Fractions Transformation of Heavy Metals in Compound Contaminated Soil Treated with Biochar, Montmorillonite and Mixed Addition

A compound contaminated soil sampled from Lingxiang City,Hunan Province,was used to investigate the effects of biochar (BC) and montmorillonite (MM) addition on heavy metals fractions.The addition amounts of BC and MM were 1%,2%,5%,respectively,and the mixture treatment was 1% BC+1% MM.BCR (European Community Bureau of Reference) sequential extraction method was used to assess the fractions of heavy metals in soil after incubation.The results indicated that adding BC alone significantly reduced the available contents of Pb,Cu and Cd.Among montmorillonite treatments,MM5% treatment decreased the weak acid extractable content of Cu,Pb,Zn,Cd by 27.6%,19.2%,25.6%,19.2%,respectively.BC+MM treatment worked well,decreased the weak acid extractable content of Cu,Pb,Zn,Cd by 15.8%,15.9%,13.1%,12.0%,and increased the residual content by 39.0%,110.1%,9.6%,62.5%,significantly reducing the mobility of the four elements.For the stabilization effect,MM treatment worked better than BC treatment,and a combination of two amendments worked the best.